Method of making interlocking elements from sheet material



W. H. COBB July 14, 1931. 1

METHOD OF MAKING INTERLOCKING ELEMENTS FROM SHEET MATERIAL Filed May 18. 1928 11V VENTOR wiZZa/rd 7'[. Cobb B Y ATTORNEY Patented July 14, 1931 UNITED STATES PATENT OFF-ICE 1 WILLARD H. COBB, F BROOKLYN, NEW YORK, ASSIGNOR TO THE SHOE HARDWARE COMPANY, OF WATERIBURY, CONNECTICUT, A CORPORATION OF CONNECTICUT METHOD OF MAKING INTERLOCKING ELEMENTS FROM SHEET MATERIAL Application filed May 18, 1928. Serial No. 278,698.

This invention relates to amethod of making interlocking elements from sheet material, more particularly to a method of making interlocking fastening elements which are associatedv in multiple series when made into a fastener.

Interlocking fastening elements of the type to which this invention more particularly relates are now in common use for fastening flexible closure edges, such as those in footwear, plackets, wearing apparel, tobacco pouches and other articles.

These fasteners comprise separate strings of fastener elements, the individual elements of which are spaced apart far enough to permit the entry, between two adjacent elements on one string, of a cooperating element on the opposite string, the elements on the opposed strings being drawn together and interlocked by a movable part known as a slider. The present invention, while not limited in its application to the making of the specific articles herein disclosed, is more particularly adapted for making interlooking fastener elements of the type above described. A11 object of the invention is to provide a simple and economical method of making interlocking fastener elements.

Another object is to provide a method of making. an interlocking fastener element which is universal, that is, the element can be interchangeably used on either side of two cooperating series of elements.

The method comprises broadly displacing material ina sheet blank to form a recess on one side and an aligned projection on the opposite side, the recess having a spherical curvature and being of less than hemispherical dimension, and further displacing material Within the area of said recess to enlarge said projection to a spherically curved surface of the same radius as to the recess but subtending a greater solid angle, the displacing operations being carried out either simultaneously or successively.

For a complete disclosure of the nature and objects of the invention reference is had to the accompanying drawings, in which 50 latter- Fig. 1 is a plan showing two series-of the elements in partial engagement, the slider for engaging them being shown in section;

Fig. 2 is a transverse section on the line 22 of Fig. 1;

Fig. 3 is a longitudinal section of two series of nested elements;

. Fig. 4 is a longitudinal section of the nested elements taken at right angles to the view in Fig. 3;

gig. 5 is a perspective of a single element; an

Fig. 6 is a perspective of a slightly modified form of element.

Referring to the drawings, the numeral 1v designates one of the elements, two partially engaged series of which are shown in Fig. 1 as anchored to the flexible supporting strips 2, and in cooperative relation with the slider 3 for engaging or disengaging the elements. Each element 1 comprises a body which is provided on one. surface adjacent its free end with a projection 4, this projection in the present instance being shown as spherically curved and substantially hemispherical. The opposite face of the element is provided with a socket or recess 5 also of general spherical contour and curved on the same radius as that of the projection 4, while at the bottom of the socket 5 is an auxiliary recess 6 extending up into the projection 4. In the preferred method of manufacture of the elements, the socket 5 is first formed by a punch of proper spherical contour cooperating with an apertured die, which operation, causes a projection to be formed on the opposite surface of the element, but which projection at this time is not of the contour or height of the projection 4. In the next operation a punch is used, of the shape of the recess 6, while the complementary 'die is recessed in the exact form of the projection 4, which latter, as before stated, has the same radius of curvature as the socket. The element is then finished by forming the clinching or securing arms 7 at its other end. The

recess 6 is technically known as a borrow recess, since the material formerly contained in it has been borrowed or transposed in order to properly ,fill out the recess in the die in which the projection 4 is formed. By reason of this construction the socket and projection have the same radius of curvature but the socket subtends a smaller solid angle than the projection, or, in other words, the socket extends into the material a less distance on the one side than the projection extends out of the material on the other side. The entire dieing operation may be per formed in one or more steps, but as the formation of the borrow recess 6 simultaneously with the socket causes greater wear on thepunohes, the previously described method is preferred.

It will be seen from an inspection of Figs. 3 and 4 that when the elements are in cooperative relation the projection 4 of one element enters the socket 5 of the next element, and the surfaces of the socket and projection directly contact, but due to the ffact that the surface of the socket subtends a smaller-solid angle than the surface of the projection,"the entire rojection cannot enter the socket, hence the elements when in nested relation are spaced from each other by reason of the extension of the curved surface of the projection 4- outside of the socket 5. Whilev in the present embodiment the projection 4 is shown as substantially hemispherical, that is, projecting above the surface of the element to a height about equal to its radius, it is obvious that this height, as well as the depth of the socket 5, may be varied, but in all cases the height will be sufficient to prevent-direct contact of the bodies of the elements with each other when in nested relation, so that adjoining elements bear on .each other only within the sockets. By this construction any two interengaging elements have substantially a ball and .socket movement with'resplect to one another and the article to whic they are attached may be freely flexed even though the elements are closely interlocked. By the improved method the interlocking projections and recesses are formed with the use of a minimum amount of metal and the stock sheetsused in making the fasteners can be of uniform thickness throughout. The method can be carried out with the use of a minimum number of tools, and while,'as before pointed out, it is preferred to perform the dieing in two operations to reduce wear on the tools,.the entire dieing may be performed in a single operation if desired. e

As the elements are all alike, they may be used interchangeably in either of the cooperating series forming the complete fastener. The flexible supporting strips 2 may be provided with corded, beaded or otherwise thickened edges over which the securing arms 7 of the elements may be clinched, but it is obvious that any other suitable forms of support and fastening for the elements may be used. By provision of the recess 6 the friction between elements is reduced since the contacting surface of the socket is less than the effective contacting,

short radius of curvature; also the flexibility of the fastener as a whole is increased; and when engaging the elements the projection on one element acts to cam the adjacent staggered element into position for nesting.

In the modification shown in Fig. 6 the element 8 is in general similar to the element 1 and is provided with a projection 4 and socket ,5 similar to the reviously described form, but the face of the free end of the element instead of being curved at all points as shown in Fig. 5 is provided with a flattened front portion 9. When the elements are engaged, this flat portion 9 is substantially in contact with the edge of the opposite supporting strip 2 and prevents pivotal or toggle movement of the engaged ends of the elements out of parallelalignment, thereby insuring against accidental disengagement of the elements.

It will be seen that by the invention a simple and efiicient method is provided for making interlocking fasteners from sheet material, and the method can be carried out latter except as is set forth in the appended claims. I

Havingthus described my invention, what I claim and desire to protect by Letters Patent is:

1. The method of forming an aligned and complementary socket and projection on opposite sides of sheet material, which comprises forming, simultaneously, a spherically curved socket on one side of less than hemispherical dimension and on the other side a projection of the same dimensions and curved on the same radius and enlarging the projection to substantially hemispherical dimensions, by flowing the material of the sheet into: the projection from a point adjacent to a portion of the surface fof the curved socket, while maintaining the superficial area of the remainder of the socket intact. j

2. The method of forming an aligned and complementary socket and projection on opposite sides of sheet material, which comprises forming, a sphericallycurved socket of desired radius on one side and a projection on the other side, and enlarging the area of the projection to a hemispherical form of the same radius as the radius of the socket, by indenting a portion of the surface of the socket and causing the material resulting from the indentation to flow into the projection.

3.- The method of forming an aligned and complementary socket and projection on opposite sides of sheet material, which comprises forming a sphericall curved socket of desired radius on one si e and a projection on the other side, and enlarging the area of the projection to a hemispherical form of the same radius as the radius of the socket, by indenting a portion of the surface ofthe socket adjacent to the apex thereof and causing the material resulting from the indentation toflow into the projection while maintaining the size and shape of the remainder of the socket intact.

4c. The method of forming an aligned and complementary socket and projection on opposite sides of sheet material, which comprises forming, by a dieing operation, a

spherically curved socket of less than hemispherical dimension on one side and an aligned projection on the opposite side, and by the second dieing operation transferring material at the base of said socket into said projection to enlarge the latter and form it into substantially a hemisphere of the same radius as the socket.

Signed at New York, county and State of New York, this 15th da of May, 1928.

W'IL ARD H. COBB. 

